After decades of research and multiple false starts, scientists are finally making headway on a long-acting, reversible birth control option for men. The experimental method involves a hormonal gel that men apply to their shoulders daily. Over time, this gel inhibits sperm production in the testes.
How does male birth control gel work?
Developed by the National Institutes of Health (NIH) and the nonprofit Population Council, the gel uses two hormones: nestorone, a progestin (synthetic progesterone), and testosterone, the male sex hormone. Nestorone suppresses testosterone production in the testes, reducing sperm development.
In normal functioning men, sperm counts range from about 15 million to 200 million sperm per millilitre of semen, and studies have shown that sperm counts of less than 1 million per millilitre are low enough to prevent pregnancy.
However, testosterone serves various roles beyond reproduction. The gel addresses this by providing sufficient testosterone to sustain normal functions such as muscle maintenance and libido, while still reducing sperm production to levels that prevent pregnancy.
Clinical trials
Since 2005, researchers have been refining the gel’s dose and concentration. In a recent trial with over 300 couples, 86% of men achieved sperm counts below 1 million per milliliter of semen—sufficient to prevent pregnancy—within 15 weeks. Some men saw results in just four to eight weeks.
“We’re really excited by the results. The combination provides better, faster suppression than expected,” said Diana Blithe, branch chief of the NIH’s National Institute of Child Health and Human Development. Blithe discussed the trial’s promising results at the Endocrine Society’s annual meeting in Boston, noting that the final data will be published in a medical journal.
Unlike female birth control, which can lead to unintended pregnancies if a dose is missed, the gel provides a buffer period. If a man misses a day or two of the gel, it takes about 8 to 10 weeks for his sperm count to recover to levels that could cause pregnancy. Additionally, the gel appears to cause fewer mood swings and depressive symptoms compared to female hormonal contraceptives.
Previous attempts at male hormonal birth control, like injections tested by the World Health Organization (WHO), were halted due to severe side effects. However, the gel’s steady hormone release from the skin seems to mitigate such issues, making it a promising candidate for male contraception.